springmvc的三種Controller處理方式及錯誤處理器
阿新 • • 發佈：2018-11-02
後端控制器主要控制資料和檢視，告知和返回給dispatcherservlet。
控制器可以有3種方法返回值
為了突出重點，先把控制器類buyProduct裡實現的3種方法發一下
1.ModelAndView
/* * 1,用modelandview傳回值和檢視，不太推薦 * */ @RequestMapping(value = "/buyProduct.do",method = {RequestMethod.POST,RequestMethod.GET}) public ModelAndView getInfo(RedirectAttributes attr, HttpServletRequest request){ ModelAndView mav=new ModelAndView(); productForm form=new productForm(); form.setName(request.getParameter("name")); form.setDescription(request.getParameter("description")); form.setPrice(Double.valueOf(request.getParameter("price"))); product p=new product(); p.setName(form.getName()); p.setDescription(form.getDescription()); p.setPrice(form.getPrice()); mav.addObject("form",form); mav.addObject("product",p); mav.addObject("name",form.getName()); mav.addObject("description",p.getDescription()); mav.addObject("price",form.getPrice()); mav.setViewName("showInfo"); return mav; }
如上，modelandview用addObject和setViewName就能完成
2.Model
/* * 2。用String傳檢視地址，model傳參 * 能將引數和檢視解耦，強力推薦 * */ @RequestMapping(value = "/buyProduct.do",method = {RequestMethod.POST,RequestMethod.GET}) public String getInfo(Model model, HttpServletRequest request){ productForm form=new productForm(); form.setName(request.getParameter("name")); form.setDescription(request.getParameter("description")); form.setPrice(Double.valueOf(request.getParameter("price"))); product p=new product(); p.setName(form.getName()); p.setDescription(form.getDescription()); p.setPrice(form.getPrice()); model.addAttribute("form",form); model.addAttribute("product",p); model.addAttribute("name",form.getName()); model.addAttribute("description",p.getDescription()); model.addAttribute("price",form.getPrice()); return "showInfo"; //重定向 // return "redirect:/showInfo.do"; //內部轉發 // return "forward:showInfo"; }
這種方法能將引數和檢視解耦，強力推薦
返回的檢視名由檢視解析器解析
本來想實現重定向和內部轉發的，但好像檢視解析器不起作用，只能絕對路徑
這個問題暫時沒找到原因
3.void
/* * 3.這種和servlet沒啥區別 * */ @RequestMapping(value = "/buyProduct.do",method = {RequestMethod.POST,RequestMethod.GET}) public void getInfo(Model model, HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { productForm form=new productForm(); form.setName(request.getParameter("name")); form.setDescription(request.getParameter("description")); form.setPrice(Double.valueOf(request.getParameter("price"))); product p=new product(); p.setName(form.getName()); p.setDescription(form.getDescription()); p.setPrice(form.getPrice()); request.setAttribute("form",form); request.setAttribute("product",p); request.setAttribute("name",form.getName()); request.setAttribute("description",p.getDescription()); request.setAttribute("price",form.getPrice()); request.getRequestDispatcher("/WEB-INF/demo1Jsp/showInfo.jsp").forward(request,response); }
這裡的model對應於jsp中EL的sessionScope，因為model是存放在session裡
這種方式適合非同步請求，就是ajax請求伺服器時，傳送的是json格式，目前還沒弄過
差點忘了貼剩下的程式碼
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/applicationContext.xml</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<display-name>dispatcher</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
</welcome-file-list>
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/demo1.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
<!--預設為0，在該servlet的第一個請求時載入
為1，在程式啟動時轉載並初始化servlet-->
</servlet>
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
</web-app>
demo1.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-4.0.xsd">
<!-- 配置controller掃描包 -->
<context:component-scan base-package="demo1Java" />
<!--使用Flash重定向傳值時必須加入
相當於配置了處理器對映器和處理器介面卡-->
<mvc:annotation-driven />
<!-- 配置檢視解析器 -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 配置邏輯檢視的字首 -->
<property name="prefix" value="/WEB-INF/demo1Jsp/" />
<!-- 配置邏輯檢視的字尾 -->
<property name="suffix" value=".jsp" />
</bean>
</beans>
product類
package demo1Java;
/**
* Created by Administrator on 2018/10/17.
*/
public class product {
private String name,description;
private double price;
public product() {
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
productForm類
package demo1Java;
/**
* Created by Administrator on 2018/10/17.
*/
public class productForm {
private String name,description;
private double price;
public productForm() {
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
}
showInfo.jsp
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2018/10/20
Time: 11:26
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>${param.name}商品資訊</title>
</head>
<body>
<%--form:${form}<br><br>
product:${product}<br><br>
商品名：${form.name}<br><br>
商品描述：${description}<br><br>
商品價格：${param.price}<br><br>--%>
<%--form:${requestScope.form}<br><br>
product:${requestScope.product}<br><br>
商品名：${requestScope.product.name}<br><br>
商品描述：${requestScope.product.description}<br><br>
商品價格：${requestScope.form.price}<br><br>--%>
form:${sessionScope.form}<br><br>
product:${requestScope.product}<br><br>
商品名：${requestScope.product.name}<br><br>
商品描述：${requestScope.product.description}<br><br>
商品價格：${requestScope.form.price}<br><br>
test311
</body>
</html>
showProduct.jsp(其實是編寫商品資訊的介面)
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2018/10/17
Time: 21:30
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>新增商品</title>
</head>
<body>
<fieldset>
<legend>請輸入要新增的商品資訊</legend>
<form action="/buyProduct.do" method="post">
請輸入商品名：<input name="name" value="" /><br><br>
請輸入描述：<textarea name="description" rows="3" cols="30" value=""></textarea><br><br>
請輸入商品價格：<input name="price" value="0.0" />
<input type="submit">
</form>
</fieldset>
</body>
</html>
錯誤處理器
異常分為兩種：預期異常和執行時異常RuntimeException
前者通過捕獲而獲取出錯資訊；
後者不用宣告也不用捕獲，主要是null和陣列越界等，主要通過規範程式碼開發、測試通過手段減少執行時異常的發生
首先，定義異常類
package ErrorSolver;
/**
* Created by Administrator on 2018/10/22.
*/
public class messageException extends Exception {
String message=null;
public messageException() {
}
public messageException(String message) {
this.message=message;
System.err.println(message);
}
@Override
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
}
異常處理類
package ErrorSolver;
import org.springframework.stereotype.Controller;
import org.springframework.web.servlet.HandlerExceptionResolver;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.io.Writer;
/**
* Created by Administrator on 2018/10/22.
*/
public class exceptionHandler implements HandlerExceptionResolver {
@Override
public ModelAndView resolveException(HttpServletRequest httpServletRequest,
HttpServletResponse httpServletResponse,
Object o, Exception e) {
ModelAndView mav=new ModelAndView();
String msg="";
if(e instanceof messageException){
msg=e.getMessage();
}else{
Writer out=new StringWriter();
PrintWriter s=new PrintWriter(out);
e.printStackTrace(s);
msg=out.toString();
}
mav.addObject("message",msg);
mav.setViewName("error");
return mav;
}
}
在demo1.xml配置異常處理Bean
<!-- 配置全域性異常處理器 -->
<bean id="handler" class="ErrorSolver.exceptionHandler"></bean>
錯誤顯示頁面error.jsp,在/WEB-INF/demo1Jsp路徑下，能被檢視解析器解析路徑
<%--
Created by IntelliJ IDEA.
User: Administrator
Date: 2018/10/22
Time: 15:40
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>錯誤處理器</title>
</head>
<body>
${message}
</body>
</html>
在showInfo.jsp下弄個測試，加上這句
1/0=<%=1/0%>
親測有效